The present invention relates to a grinding and finishing apparatus for mechanically working an optical element or the like by grinding and finishing processes and a method of grinding and finishing the optical element or the like. More particularly, the present invention relates to an apparatus for grinding and finishing a body to be worked (workpiece) which comprises a workpiece carrying shaft for holding a workpiece so as to rotatively drive or rotate it about its axis, and a tool carrying shaft for holding a tool on the same axis as that of the workpiece shaft and constituted so as to be capable of rotating and driving through a drive means, thereby grinding and finishing a workpiece to be worked by rotating the workpiece and the tool with each other, and a method of grinding and finishing the optical element.
The conventional grinding and finishing apparatus has been well known from a lens grinding or finishing apparatus described in Japanese Utility Model Application No. 13,439/68. As shown in FIGS. 7 and 8, such a lens grinding apparatus comprises a swinging or swivel frame 2 pivoted by or supported by horizontal shafts 1, 1, lower dish member supporting shaft 3 provided at right angles to the horizontal shafts and capable of controlling ascending and descending motion thereof, a crank plate member 4 connected to a swinging drive source, and a swinging arm member 11 having a guide slot 10. The swinging arm member 11 is, on the one hand, attached to the crank plate member 4 by a sliding member 6 engaged to an adjusting screw 5 arranged to the crank plate member 4 in a relation of screw pair or a setscrew 7, and is, on the other hand, attached to the horizontal shafts 1, 1 by a setscrew 9 through an arc shaped slot 8 so as to adjust its attached position. The swinging frame 2 may be swung around the shaft center of the horizontal shafts 1 by slidable connection of the setscrew 7 and the swinging arm member 11 so as to be capable of controlling its angular amplitude and its center position. An upper dish member supporting shaft 12 and a lower dish member supporting shaft 3 are arranged to make the upper dish member supporting shaft 12 ascending and descending operable above a lower dish 14, and then these supporting shafts 3 and 12 are rotated forcibly through a wrapping connector driving mechanism, so that a lens member 15 may be ground between an upper dish 13 and the lower dish 14.
According to the above lens grinding and finishing apparatus, the upper dish 13 and the supporting shafts 12 and 3, respectively, and the upper and lower supporting shafts 12 and 3 are rotated and the swinging frame 2 is swung, while providing the surface to be ground of the lens material 15 with abrasive, so that the lens material 15 may be ground.
The above conventional lens grinding apparatus has a working means for swinging the lower dish 14 with angular amplitude about an angular amplitude swinging center set on an axis of the lower dish supporting shaft 3, so that when the upper dish 13 is worked under the state fixed to the lower end of the upper dish supporting shaft 12, the working must be performed under the state corresponding the sphere center of the lower dish 14 to the angular amplitede swinging center of the lower dish supporting shaft 3, and thus a space of length corresponding to radius of curvature of the lower dish 14 must be provided above the lower dish supporting shaft 3, and thus it is very difficult to correspond the apparatus to various or whole radius, in practice.
In the above conventional lens grinding apparatus, it is also considered that the upper dish member 13 is not fixed to the lower end of the upper dish member supporting shaft 12 and is held so as to slant it to the upper dish supporting shaft 12 and thus to absorb the disagreement of the swinging shaft to the spherical center of the lower dish member 14. In this case, problems lie in that the angle between the upper dish supporting shaft 12 and the upper dish 14 becomes too large and the control of the working conditions becomes difficult.